Thermal feedback systems and methods of using the same

ABSTRACT

A system for providing feedback during an electrosurgical procedure on a target tissue is provided. The system includes an electrosurgical energy source; an electrode probe assembly connected to the electrosurgical energy source, wherein the electrode probe assembly includes at least one electrode assembly having a needle configured to deliver electrosurgical energy to the target tissue; at least one thermal feedback assembly connected to the electrosurgical energy source, wherein each thermal feedback assembly includes at least one temperature sensor assembly; and a hub configured to selectively support the electrode probe assembly and each thermal feedback assembly such that the needle of the electrode probe assembly and each temperature sensor assembly of each thermal feedback assembly are proximate one another when disposed proximate the target tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/066,050, now U.S. Pat. No. 8,956,350, filed Oct.29, 2013, which is a continuation application of U.S. patent applicationSer. No. 13/539,725, now U.S. Pat. No. 8,568,402, filed Jul. 2, 2012,which is a divisional application of U.S. patent application Ser. No.12/023,606, now U.S. Pat. No. 8,211,099, filed Jan. 31, 2008, whichclaims the benefit of and priority to U.S. Provisional Application Ser.No. 60/887,537, filed on Jan. 31, 2007, the entire contents of all ofwhich are incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to energy delivery feedback systems and,more particularly to thermal feedback systems for electrosurgical energysystems and methods of their use.

2. Background of Related Art

The use of electrical energy including radiofrequency and microwaveenergy (“RF & MW energy”) and, in particular, radiofrequency electrodesor microwave antennae (“RF-electrodes/MW-antennae”) for ablation oftissue in the body or for the treatment of pain is known. Generally,such RF electrodes (e.g., probes, resistive heating elements and thelike) include an elongated cylindrical configuration for insertion intothe body to target tissue which is to be treated or ablated. The RFelectrodes can further include an exposed conductive tip portion and aninsulated portion. The RF electrodes can also include a method ofinternal cooling (e.g., a Cool-Tip™ or the like), such as the RFelectrodes shown and described in U.S. Pat. No. 6,506,189 entitled“COOL-TIP ELECTRODE THERMOSURGERY SYSTEM” issued to Rittman, III et al.,on Jan. 14, 2003 and U.S. Pat. No. 6,530,922 entitled “CLUSTER ABLATIONELECTRODE SYSTEM” issued to Cosman et al., on Mar. 11, 2003, the entirecontent of which is incorporated herein by reference. Accordingly, whenthe RF electrode is connected to an external source of radiofrequencypower, e.g., an electrosurgical generator (device used to generatetherapeutic energy such as radiofrequency (RF), microwave (MW) orultrasonic (US)), and current is delivered to the RF electrode, heatingof tissue occurs near and around the exposed conductive tip portionthereof, whereby therapeutic changes in the target tissue, near theconductive tip, are created by the elevation of temperature of thetissue.

In some applications, for example, tumor ablation procedures, multipleelectrodes are inserted into the body in an array to enlarge ablationvolumes.

In a particular application, arrays of high frequency electrodes areinserted into tumors. The electrodes are typically placed in a dispersedfashion throughout the tumor volume to cover the tumor volume withuniform heat. The multiple electrodes may be activated simultaneously orsequentially applied with high frequency energy so that each electrodeheats the surrounding tissue. During series activation, energy isapplied to each electrode one at a time. This sequence of cycling theenergy through the electrodes continues at a prescribed frequency andfor a period of time.

The electrode systems discussed above are limited by the practical sizeof lesion volumes they produce. Accordingly, electrodes with cooledconductive tips have been proposed. With cooling, radiofrequencyelectrode tips generally produce larger lesion volumes compared withradiofrequency electrodes, which are not cooled. For example, standardsingle cylindrical electrodes, with cooled tips, as described above, maymake lesion volumes up to 2 to 3 cm in diameter in living tissue (e.g.,the liver) by using needles of 1 to 2 mm in diameter and having exposedtip lengths of several centimeters.

SUMMARY

The present disclosure relates to thermal feedback systems forelectrosurgical energy systems and methods of their use.

According to an aspect of the present disclosure, a system for providingfeedback during an electrosurgical procedure on a target tissue isprovided. The system includes an electrosurgical energy source; anelectrode probe assembly connected to the electrosurgical energy source,wherein the electrode probe assembly includes at least one electrodeassembly having a needle configured to deliver electrosurgical energy tothe target tissue; at least one thermal feedback assembly connected tothe electrosurgical energy source, wherein each thermal feedbackassembly includes at least one temperature sensor assembly; and a hubconfigured to selectively support the electrode probe assembly and eachthermal feedback assembly such that the needle of the electrode probeassembly and each temperature sensor assembly of each thermal feedbackassembly are proximate one another when disposed proximate the targettissue.

The needle of the electrode probe assembly may include an electricallyconductive distal tip electrically connected to the electrosurgicalenergy source.

The electrode probe assembly may be fluidly connected to a coolantsupply and may be configured to receive a circulating fluid therein.

The thermal feedback assembly may include a one or more temperaturesensors. Each temperature sensor may be oriented substantially parallelto an axis defined by the needle of the electrode probe assembly orprotrude 90 degrees from the center exposed active electrode. Theplurality of temperature sensors may be arranged in a linear array. Theplurality of temperature sensors may be disposed on opposed sides of theneedle of the electrode probe assembly. The plurality of temperaturesensors may be uniformly spaced from one another. The plurality oftemperature sensors may be arranged in one of a linear, rectilinear anda triangular array.

The system may further include a computer connected to at least one ofthe electrosurgical energy source, the electrode probe assembly and eachthermal feedback assembly. In an embodiment, at least one of theelectrosurgical or microwave generator, the electrode probe assembly andeach thermal feedback assembly may transmit information to the computer,and wherein the computer performs an Arrhenius model calculation on theinformation received from the at least one of the electrosurgical energysource, the electrode probe assembly and each thermal feedback assembly.

The temperature sensors may include fiber optic temperature probes,thermisters, thermocouples or resistive temperature devices (RTD).

According to another aspect of the present disclosure, a method ofperforming a thermal treatment on a target tissue is provided. Themethod comprises the steps of providing an electrosurgical energysource; and providing a thermal feedback system. The thermal feedbacksystem includes an electrode probe assembly connectable to theelectrosurgical generator, wherein the electrode probe assembly includesat least one electrode assembly having a needle configured to deliverelectrosurgical energy to the target tissue; at least one thermalfeedback assembly connectable to the electrosurgical energy source,wherein each thermal feedback assembly includes at least one temperaturesensor assembly; and a hub configured to selectively support theelectrode probe assembly and each thermal feedback assembly such thatthe needle of the electrode probe assembly and each temperature sensorassembly of each thermal feedback assembly are proximate one anotherwhen disposed proximate the target tissue.

The method further includes the steps of inserting the needle of theelectrode probe assembly and each temperature sensor of the thermalfeedback assembly into a patient proximate the target tissue; activatingthe electrosurgical energy source for delivering electrosurgical energyto the target tissue via the needle of the electrode probe; andmonitoring and transmitting changes in a characteristic of the targettissue to the electrosurgical energy source via the temperature sensorsof the thermal feedback assembly.

The method may further include the step of performing an Arrhenius modelcalculation on the information received from each thermal feedbackassembly.

The method may further include the step of selecting a particularelectrode probe assembly for a particular thermal procedure or desiredtreatment size or volume. Size estimation may be accomplished prior todelivery of the electrode probe assembly. The method may further includethe step of selecting a characteristic energy value to be delivered tothe particular electrode probe assembly based on the characteristics ofthe electrode probe assembly and the characteristics of the targettissue to be treated.

The method may further include the step of providing feedback to theelectrosurgical energy source from the plurality of thermal feedbackprobes. Size estimation may be conducted during energy activation.

The method may further include the step of providing a computerconfigured to receive information regarding characteristics of at leastone of the target tissue, the feedback of energy delivery, the electrodeprobe assembly, the thermal feedback assembly and the electrosurgicalenergy source. The computer may be configured to receive feedbackinformation from the thermal feedback assembly during a thermaltreatment of the target tissue. The computer may be configured toperform an Arrhenius model calculation or other ablation size estimationon the information received from each thermal feedback assembly.

The method may further include the step of arranging the electrode probeassembly and each thermal feedback assembly in a linear array.

The method may further include the step of spacing the thermal feedbackassemblies equally from each other and from the electrode probeassembly.

The method may further include the step of spacing the thermal feedbackassemblies at a known or predetermined spacing.

The method may further include the step of circulating a fluid throughthe electrode probe assembly.

The method may further include the step of introducing the electrodeprobe assembly and each of the plurality of thermal feedback assembliesinto the target tissue.

These and other aspects and advantages of the disclosure will becomeapparent from the following detailed description and the accompanyingdrawings, which illustrate by way of example the features of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the system and method of use of the system of thepresent disclosure will become more readily apparent and may be betterunderstood by referring to the following detailed descriptions ofillustrative embodiments of the present disclosure, taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a schematic illustration of a thermal feedback systemillustrating an electrode probe assembly and a thermal feedback assemblyof the present disclosure operatively associated with a target surgicalsite;

FIG. 2 is an illustration of the thermal feedback system of FIG. 1;

FIG. 2A is a schematic distal end view of the thermal feedback system ofFIG. 2, illustrating the temperature array in a linear arrangement;

FIG. 2B is a schematic distal end view of an alternate arrangement ofthe thermal feedback system of FIG. 2, illustrating the temperaturearray in a rectangular arrangement;

FIG. 2C is a schematic distal end view of a further alternatearrangement of the thermal feedback system of FIG. 2, illustrating thetemperature array in a triangular arrangement;

FIG. 2D is a schematic distal end view of the thermal feedback system ofFIG. 2, illustrating the temperature array in an alternate lineararrangement;

FIG. 3 is an illustration of a feedback/monitoring assembly of thethermal feedback system;

FIG. 4 is an enlarged view of the indicated area of detail of FIG. 3;

FIG. 5 is a schematic illustration of a distal end of an electrode probeassembly according to a further embodiment of the present disclosure;

FIG. 6 is a distal end view of an electrode probe assembly similar tothe electrode probe assembly of FIG. 5;

FIG. 7A is a schematic illustration of a distal end of an electrodeprobe according to an embodiment of the present disclosure; and

FIG. 7B is a distal, elevational view of the electrode probe of FIG. 7A.

DETAILED DESCRIPTION OF EMBODIMENTS

The systems and methods of the present disclosure provide for a moreprecise controlled monitoring and/or feedback of an electrode probeduring therapeutic use in a target surgical site, e.g., in a cancertumor. Moreover, the systems and methods of the present disclosureprovide for an improved ability to predict and/or estimate the depthand/or volume of treatment possible by the electrode probe when theelectrode probe of an electrosurgical treatment device is set to aparticular or various operative parameters.

It will be readily apparent to a person skilled in the art that thesystems and methods of use of the systems can be used to monitor orprovide feedback during treatment of body tissues in any body cavity ortissue locations that are accessible by percutaneous or endoscopiccatheters or open surgical techniques, and is not limited to cancertumors or the like. Application of the systems and methods in anycorporal organ and/or tissue is intended to be included within the scopeof the present disclosure.

1. System for Thermal Feedback

In the drawings and in the description which follows, the term“proximal”, as is traditional, will refer to the end of the system, orcomponent thereof, which is closest to the operator, and the term“distal” will refer to the end of the system, or component thereof,which is more remote from the operator.

With reference to FIG. 1, a thermal feedback system, according to anembodiment of the present disclosure, is generally designated as 100.Feedback system 100 includes a thermal feedback assembly 200 operativelyconnected to an electrosurgical generator and/or energy source 10 and/orcomputer 20.

At least one electrode probe assembly 300 is provided which isoperatively associated with feedback assembly 200 and is connectable toelectrosurgical energy source 10 in order to perform tissue ablation andthe like. Each electrode probe assembly 300 may include a rigid shaft,antenna or needle 310 configured for insertion into a target tissue ororgan “OR”. Needle 310 of each probe assembly 300 may terminate in anexposed distal tip 312 having a pointed configuration for facilitatingpercutaneous insertion of needle 310 into body organ “OR”. A portion ofthe external surface of needle 310 of each electrode probe assembly 300is covered with an insulating material, as indicated by hatched lineareas in FIG. 1. Distal tip 312 remains uncovered and is connected,through needle 310, to cable 12 and thereby to electrosurgical energysource 10. Electrode probe assembly 300 may include a coolant supply 30fluidly connected to needle 310 for circulating a fluid thereto viaconduit(s) 32.

Reference may be made to commonly assigned U.S. application Ser. No.11/495,033, filed on Jul. 28, 2006, and entitled “COOL-TIP THERMOCOUPLEINCLUDING TWO-PIECE HUB” for a detailed discussion of the constructionand operation of electrode probe assembly 300.

Temperatures at, or near the exposed distal tip(s) 312 of needle(s) 310may be controlled by adjusting a flow of fluid coolant through needle310. Accordingly, the temperature of the tissue contacting at or neardistal tip(s) 312 is controlled. In operation, fluid from coolant supply30 is carried the length of needle 310 through an inner tube (not shown)extending therethrough to the distal end of needle 310 terminating in anopen end or cavity (not shown) of distal tip 312. At the opposite end ofneedle 310, the inner tube is connected to receive fluid. Backflow fromdistal tip(s) 312 is through an exit port (not shown) of needle 310.

Feedback system 100 may further include a reference electrode 40 thatmay be placed in contact with the skin of a patient or an externalsurface of organ “OR” with a connection 42 to electrosurgical energysource 10. Reference electrode 40 and connection 42 serve as a path forreturn current from electrosurgical energy source 10 through needle 310of electrode probe assembly 300.

As seen in FIG. 1, by way of illustration only, a targeted region to beablated is represented in sectional view by the line “T”. It is desiredto ablate the targeted region “T” by fully engulfing targeted region “T”in a volume of lethal heat elevation. The targeted region “T” may be,for example, a tumor which has been detected by an image scanner 50. Forexample, CT, MRI, fluoroscopy or ultrasonic image scanners may be used,and the image data transferred to computer 20. As an alternate example,an ultrasonic scanner head 52 may be disposed in contact with organ “OR”to provide an image illustrated by lines 52 a.

For example, in FIG. 1, dashed line “T1” represents the ablationisotherm in a sectional view through organ “OR”. Such an ablationisotherm may be that of the surface achieving possible temperatures ofapproximately 50° C. or greater. At that temperature range, sustainedfor approximately 30 seconds to approximately several minutes, tissuecells will be ablated. The shape and size of the ablation volume, asillustrated by dashed line “T1”, may accordingly be controlled by aconfiguration of the electrode probe assemblies 300 used, the geometryof distal tips 312 of electrode probe assemblies 300, the amount of RFpower applied, the time duration that the power is applied, the coolingof the needles 310 of electrode probe assemblies 300, etc.

Data processors may be connected to display devices to visualizetargeted region “T” and/or ablation volume “T1” in real time during theablation procedure.

As seen in FIG. 1, feedback system 100 may further include a library 60including a plurality of thermal profiles/overlays 62 _(n). As usedherein, the term library is understood to include and is not limited torepository, databank, database, cache, storage unit and the like. Eachoverlay 62 includes a thermal profile which is characteristic of and/orspecific to a particular configuration of cannula/electrode assembly oramount of exposure (i.e., specific to the length of exposure of distaltip 312 of needle 310 or the amount of needle 310 extending from adistal tip of a cannula) of the cannula/electrode assembly. In addition,for each amount of exposure or configuration of the cannula/electrodeassembly, a plurality of overlays 62 _(n) is provided which includes athermal profile which relates to, for example, the amount of timeelectrode probe assembly 300 is activated, to the temperature to whichelectrode probe assembly 300 is heated, etc.

With continued reference to FIG. 1, feedback system 100, as mentionedabove, includes a thermal feedback assembly 200 operatively connected toan electrosurgical generator 10 and/or computer 20. Thermal feedbackassembly 200 is operatively associated with the at least one electrodeprobe assembly 300.

As seen in FIG. 1, feedback assembly 200 includes a hub or housing 210configured to selectively support at least one electrode probe assembly300 and at least one temperature sensor assembly 220. As seen in FIG. 1,a plurality of temperature sensor assemblies 220 are shown supported inhousing 210 on opposed sides of a single electrode probe assembly 300.It is contemplated that any number of temperature sensor assemblies 220may be disposed on a single side, on opposed sides, or on multiple sidesof the single electrode probe assembly 300 or relative to multipleelectrode probe assemblies 300. It is further contemplated that multipletemperature sensor assemblies 220 may be interspersed amongst multipleelectrode probe assemblies 300. Individual needles, cannula orintroducers 223 may be used to introduce temperature sensors 222 intothe target site or organ “OR”.

As seen in FIG. 2, housing 210 is used to position temperature sensorassemblies 220 on opposed sides of a singe electrode probe assembly 300so as to define a single axis or plane. Housing 210 may be configured toposition cannula 223 and temperature sensors 222 of temperature sensorassemblies 220 at a known distance from electrode probe assembly 300and/or from one another, or are equi-distant or uniformly spaced fromone another.

As seen in FIG. 2A, temperature sensors 222 and electrode assembly 310are arranged in a linear array. As seen in FIG. 2B, temperature sensors222 and electrode assembly 310 may be arranged in a rectilinear array.As seen in FIG. 2C, temperature sensors 222 and electrode assembly 310may be arranged in a triangular array. As seen in FIG. 2D, temperaturesensors 222 are arranged at a known distance from electrode assembly310. As seen in FIGS. 2-2D, electrode assembly 310 is located at thecenter of temperature sensors 222; however, electrode assembly 310 maybe located at any position relative to sensors 222.

Each temperature sensor assembly 220 is electrically or opticallyconnected to electrosurgical generator 10 via a suitable electricalconnector or the like 230.

Temperature sensors 222 include one or more of an emitter, sensor ormarker to provide special relationship to electrode assembly 310. Eachtemperature sensor assembly 220 may include a temperature sensor 222 inthe form of a rigid or semi-rigid cannula 223 and/or needles configuredfor insertion and/or penetration into the target surgical site. Suitabletemperature sensors 222 may include thermocouples, resistive temperaturedevices (RTD) or fiber optic temperature probes sold under the tradename“Fluoroptic® Thermometer, available from Luxtron®, Santa Clara, Calif.Temperature sensors 222 are shown and described in U.S. Pat. Nos.4,075,497; 4,215,275; 4,448,547; 4,560,286; 4,752,141; 4,883,354; and4,988,212.

Fluoroptic® temperature sensors 222 are configured to measure the decaytime of light emitted from phosphorescent materials (e.g., phosphors).The decay time is a persistent property of the sensor that variesdirectly with the temperature.

Other suitable temperature sensors for use with temperature sensorassemblies 220, to measure the temperature at a target surgical site,include and are not limited to optical sensors (e.g., Flouroptic®,infrared, etc.), thermocouples, Resistance-Temperature-Detectors (RTD),thermistors, MRI, fluoroscopic, ultrasound, CT and the like.

Temperature sensors 222 may be configured to measure or monitortemperatures greater than about 60° C. In an embodiment, feedback system100 may be provided with suitable algorithms or the like forinterpolating temperature values from at least two temperature sensors222 and/or for integrating thermal damage from at least two temperaturesensors 222. One real-time temperature sensor may be used in conjunctionwith an assumed or predetermined value from a look-up table or similarmethod.

The temperature measurements delivered to feedback system 100 may beused to generate a thermal map of the target area and/or, uponintegration, may be used to account for particular tissuecharacteristics, such as, for example, perfusion, conduction, resistanceand/or density.

In an embodiment, temperature sensors 222 may be deployed around needle310 of the electrode probe assembly 300. Such temperature sensors may beconstructed of suitable shape memory alloys so as to permit thetemperature sensor to wrap around needle 310. Additionally, in anembodiment, a cannula including temperature sensors may be deployedabout needle 310 of the electrode probe assembly 300. In anotherembodiment, as seen in FIGS. 7A and 7B, temperature sensors 222 mayprotrude at a substantially right angle from a center or mid point ofthe exposed distal tip 312 of needle 310.

Electrosurgical generator 10 and electrode probe assembly 300 may beconfigured to deliver energy to at least one of a radiofrequency, amicrowave, an ultrasound, and a cryo-therapy needle.

Feedback system 100 is capable of providing size predictability forablation volume to be created during a thermal procedure of a targetregion prior to the ablation volume exceeding a predetermined volumeduring the thermal procedure. For example, feedback system 100 mayprovide feedback regarding a volume of the thermal therapy (e.g.,diameter), and estimation of an overall size of the volume of thethermal therapy, an estimation of a rate of growth of the volume of thethermal therapy, and/or an estimation of a time to completion of thethermal therapy. All of this information may be displayed on a monitor54 (See FIG. 1) or the like. Additionally, monitor 54 may illustrate thegrowth of the ablation volume, in real-time, as the procedure is goingforward.

As seen in FIGS. 5-7, a distal end of electrode probe assembliesaccording to further embodiments of the present disclosure are generallydesignated as 300′ and 300″, respectively. Electrode probe assembly300′, 300′″ is substantially similar to electrode probe assembly 300 andthus will only be discussed in further detail herein to the extentnecessary to identify differences in construction and operation thereof.

As seen in FIGS. 5 and 7, distal tip 312′ of electrode probe assembly300′ has a length of exposure “L”. Additionally, electrode probeassembly 300′ is configured such that temperature sensor 222′ extendsradially outward therefrom at a location approximately equal to “L/2”.As seen in FIG. 5, temperature sensor 222′ may extend radially andlinearly from electrode probe assembly 300′ (e.g., in a plane that issubstantially orthogonal to a longitudinal axis of electrode probeassembly 300′), or, as seen in FIG. 6, temperature sensor 222″ mayextend radially and arcuately from electrode assembly 300″ (e.g., in aplane that is substantially orthogonal to a longitudinal axis ofelectrode probe assembly 300″).

As seen in FIG. 5, a single temperature sensor 222′ may extend fromelectrode assembly 300′, and as seen in FIG. 6, a pair of temperaturesensors 222″ may extend from electrode assembly 300″. In any of theembodiments disclosed herein, any number of temperature sensors 222′ or222″ may be used to extend from electrode assembly 300′, 300″ or 300′″.

Each temperature sensor 222′ or 222″ may include at least one, and asseen in FIGS. 5 and 6, a plurality of discrete respective temperaturesensor elements 222 a′, 222 a″ disposed along a length thereof, such as,for example, at least at a tip thereof, at a mid-point thereof and at abase or proximal end thereof.

As seen in FIGS. 5 and 6, each temperature sensor 222′ or 222″ may beslidably disposed within a respective electrode probe assembly 300′,300″ and configured so as to project and/or retract from withinelectrode probe assembly 300′ or 300″. Each temperature sensor 222′,222″ may extend along an outer surface of a respective electrode probeassembly 300′, 300″.

Each temperature sensor 222′, 222″ may be deployable to a known and/orpredetermined radial distance from respective distal tips 312′, 312″ ofrespective electrode probe assembly 310′, 310″. In accordance with FIG.6, or in embodiments employing multiple temperature sensors 222″, themultiple temperature sensors 222″ may be deployed to a known and/orpredetermined distance from one another.

As seen in FIG. 7, temperature sensors 222′″ may be disposed to a knownand/or predetermined radial distance from electrode probe assembly300′″. Temperature sensors 222′″ are generally disposed L/2 and ½desired diameter of thermal ablation (W/2), wherein “L” is the length ofexposure of the distal end of electrode probe assembly 300′″ and “W” isthe approximate diameter of the thermal ablation.

2. Method for Thermal Feedback

With reference to FIGS. 1-7B, a method of using thermal feedback system100 during the thermal treatment of a target tissue or organ “OR” withelectrode probe assembly 300, 300′ or 300″, in conjunction withhyperthermia feedback assembly 200, is described.

A method of the present disclosure includes determining a zone ofthermal treatment during and/or post treatment of the target tissue ororgan “OR”. The method may comprise the step of measuring a temperatureof the target tissue or organ “OR”, at known distances relative thereto,during and/or post treatment of the target tissue or organ “OR”. Thetemperature of the target tissue or organ “OR”, at the known distance,may be an absolute temperature and/or a temperature that isinterpolated. Additionally, the method may comprise integrating thetemperature over time to determine an extent of thermal treatment. Suchan integration may be calculated using an “Arrhenius thermal treatmentintegral” or other methods of thermal damage estimation.

As used herein, “thermal damage” is a term that describes a quantityrepresenting a relative amount of destruction to a tissue component. Thecomponent of interest can vary widely between applications fromsub-cellular components, such as, for example, protein or organelles, tomany celled systems, such as, for example, tumors or organs. To studysystems spanning such a wide range of scale different techniques may beapplied. For a relatively small system, one approach may be an “abinitio” method or some other molecular dynamic approach. For relativelylarger systems, one approach may be to use an empirical method, such as,for example, the “Arrhenius” method described herein or a criticaltemperature criterion.

The term “Arrhenius thermal treatment” refers to a method of quantifyingthermal effects on underlying tissue. The present method thus modelsmicroscopic effects in tissue, such as, for example, the denaturation ofa single species of protein, or models macroscopic effects in tissue,such as, for example, a color change of the tissue associated with thethermal treatment where many different reactions have taken place.

The equation for the “Arrhenius model” may be represented by thefollowing equation:

${\Omega(t)} = {{- {\ln( \frac{c(t)}{c(o)} )}} = {A{\int_{0}^{t}{e^{(\frac{{- \Delta}\; E}{R\; T})}\ d\; t}}}}$

where:

Ω=is the thermal effect sustained by the tissue or organ;

c(t)=is the amount of the component of interest remaining;

c(0)=is the amount of the component of interest at time zero;

A=is the frequency factor, approximately 7.39×10³⁹ l/s (specific toliver tissue); and

ΔE=is the activation energy, approximately 2.577×10⁵ J/mol (specific toliver tissue).

The “Arrhenius model” is used because, in addition to combinedprocesses, the “Arrhenius model” applies to individual processes aswell. Individual processes that may be of interest include and are notlimited to the denaturation of a lipid bi-layer of a cell, thedenaturation of mitochondrial proteins, and the denaturation of nuclearproteins. The denaturation of lipid bi-layer is of interest because thelipid bi-layer loses its structure before many other parts of a cell.The denaturation of mitochondrial and nuclear proteins is of interestbecause they denature at temperatures in the range of about 42 to 60° C.

A method of the present disclosure may also include the step of using aposition of electrode probe assembly 300, 300′ or 300″ and needle 310,positional temperature and/or feedback temperature received fromhyperthermia feedback assembly 200 to determine the extent of thermaleffect or treatment to the target tissue or organ “OR”. The position ofelectrode probe assembly 300, 300′ or 300″ and needle 310 may bedetermined using a suitable positional indicator. The positionaltemperature may be determined by the location of temperature sensor 222,222′, 222″ or 222′″ and may be used to determine the presence of thelack of heat in the tissue or organ “OR”.

A method of the present disclosure may also include the step ofdetermining the spatial relationship between electrode probe assembly300 and temperature sensor 222. Spatial relationship of electrode probeassembly 300 and temperature sensor 222 and temperature measured attemperature sensor 222 are feedback to computer 20 to determine anextent of thermal damage that may be displayed on monitor 54 or used toalter the output of electrosurgical energy source 10.

A method of the present disclosure may use a three-dimensional (3D)thermal image/map to determine a dimension of thermal treatment of thetarget tissue of organ “OR”.

According to a method of the present disclosure, computer 20 of feedbacksystem 100 is provided with information regarding a location of thetarget tissue or organ “OR”, a location of critical biologicalstructures (e.g., tissue, organs, vessels, etc.), a size and/or shape ofthe tumor or the target tissue or organ “OR” to be thermally treated,and a desired size of the thermal treatment volume. With thisinformation inputted into computer 20, computer 20 may apply the“Arrhenius model” in order to develop a course of treatment.

According to a method of the present disclosure, an electrode probeassembly 300, 300′ or 300″ including a particular needle 310 having agiven length “L” of exposure of distal tip 312 thereof is selected for aparticular thermal procedure. A length “L” of electrode exposure may beuser selected based on a desired volume of tissue to be treated ordiameter “W” of thermal treatment. With the particular electrode probeassembly 300, 300′ or 300″ selected the parameters (e.g., dimensions,power rating, etc.) of electrode probe assembly 300, 300′ or 300″ ismanually inputted or automatically selected from a look-up table for useby the electrosurgical generator 10 and/or computer 20.

With the parameters or characteristics of the tumor, target tissue ororgan “OR” inputted into the electrosurgical energy source 10 and/orcomputer 20 and the parameters or characteristics of the electrode probeassembly 300, 300′ or 300″ selected also inputted into theelectrosurgical generator 10 and/or computer 20, the parameters of theenergy to be delivered to the tumor, target tissue or organ “OR”, viathe electrode probe assembly 300, 300′ or 300″, are determined. As seenin FIG. 1, with the parameters of the energy to be delivered determined,thermal feedback assembly 200 and with electrode probe assembly 300inserted into the patient, proximate the tumor, target tissue or organ“OR”. In particular, temperature sensors 222 of thermal feedbackassembly 200 and needle 310 of electrode probe assembly 300 may beinserted into the tumor, target tissue or organ “OR”.

With thermal feedback assembly 200 and electrode probe assembly 300positioned, the placement of thermal feedback assembly 200 and electrodeprobe assembly 300 is confirmed. Next, a spatial relationship oftemperature sensors 222 and electrode probe assembly 300 may bedetermined by using thermal feedback assembly 200 or use of othermarkers, and communicated to electrosurgical energy source 10 and/orcomputer 20 for use of feedback control of energy parameter and/or sizeestimation. After confirmation of the placement of thermal feedbackassembly 200 and electrode probe assembly 300 the thermal treatment ofthe tumor, target tissue or organ “OR” may begin. The thermal treatmentof the tumor, target tissue or organ “OR” includes delivering energyproduced by electrosurgical generator 10 to the tumor, target tissue ororgan “OR” via electrode probe assembly 300.

During the thermal treatment of the tumor, target tissue or organ “OR”hyperthermia feedback assembly 200 provides feedback to electrosurgicalenergy source 10 and/or computer 20 in the manner described above.Treatment progress is determined by computer 20 with feedback from atleast one of image scanner 5, electrosurgical energy source 10, andtemperature sensors 222. Treatment progress is displayed on monitor 54.Treatment progress includes one of size estimation, rate of treatmentprogression, and relationship of treatment volume to target volume.

While the above description contains many specific examples, thesespecific should not be construed as limitations on the scope of thedisclosure, but merely as exemplifications of preferred embodimentsthereof. Those skilled in the art will envision many other possiblevariations that are within the scope and spirit of the disclosure asdefined by the claims appended hereto.

What is claimed is:
 1. A system comprising: an electrosurgical generatorconfigured to generate microwave energy; an antenna assembly configuredto couple to the electrosurgical generator and deliver the generatedmicrowave energy to tissue; a thermal feedback assembly including aplurality of temperature sensor assemblies, the thermal feedbackassembly configured to measure a temperature of tissue during deliveryof the generated microwave energy to tissue and transmit the measuredtemperature to the electrosurgical generator; and a hub configured tosupport the antenna assembly and the thermal feedback assembly such thatthe antenna assembly and each temperature sensor assembly of the thermalfeedback assembly are proximate to one another when disposed proximatetissue.
 2. The system according to claim 1, wherein the electrosurgicalgenerator is further configured to control generation of microwaveenergy based on the measured temperature.
 3. The system according toclaim 1, wherein the electrosurgical generator is further configured toestimate a desired thermal treatment volume based on the measuredtemperature.
 4. The system according to claim 1, further comprising acoolant supply fluidly coupled to the antenna assembly, the coolantsupply configured to circulate a coolant fluid through the antennaassembly.
 5. The system according to claim 1, wherein the thermalfeedback assembly is configured to measure temperature proximate adistal portion of the antenna assembly.
 6. The system according to claim1, wherein the antenna assembly includes an inner tube configured tocirculate coolant fluid therethrough.
 7. The system according to claim1, wherein the hub is configured to house a portion of the antennaassembly and circulate coolant fluid therethrough.
 8. The systemaccording to claim 1, wherein the antenna assembly includes a distalradiating portion configured to deliver the generated microwave energy.9. The system according to claim 1, wherein the thermal feedbackassembly includes at least one of a temperature sensor or athermocouple.